Twisted wire mascara brushes have been known for many years. Such brushes 10 as shown in FIG. 1 comprise a plurality of straight bristles 12 extending generally outwardly from an axial core of twisted wires 14 and forming a spiral pattern along the length of the wires 14, the bristles 12 being anchored at their midpoints 16 by being trapped between the twisted wires 14. As seen in FIG. 1, these prior cosmetic brushes 10, while defining a generally cylindrical outline, have a large spiral gap 18 lying adjacent the spiral pattern defined by the trapped bristles 12.
Such spiral pattern is a natural consequence of the method of making the brush 10 by trapping and pinching the straight bristles 12 between the twisted wires 16. This method is simple, effective and long established, and consequently mascara brushes are, insofar as is known, always made in this configuration even though the spiral pattern does not provide the best mascara brush from a functional standpoint. The patent literature almost invariably shows mascara brushes having this spiral pattern (e.g. the U.S. patents to Cassai et al U.S. Pat. No. 4,428,388; Mantelet U.S. Pat. No. 4,056,111; U.S. Pat. No. Kingsford 4,332,494 and Masters et al U.S. Pat. No. 3,214,782; Cassai U.S. Pat. No. Des. 282,107 and Hahn U.S. Pat. No. Des. 122,109), an exception being the ancient Mason U.S. Pat. No. Des. 27,010. The twisted wire method includes a second step which is known as "rifling", an operation in which the bristle ends are trimmed or chiseled to give the brush its overall exterior configuration. This rifling operation does not modify the aforementioned spiral pattern.
The spiral pattern mascara brush has the significant functional disadvantage of non-uniformity. It does not pick up cosmetic, e.g. mascara, uniformly and it does not deposit the mascara uniformly. In spite of these functional disadvantages, the spiral pattern twisted wire mascara brush has remained the industry standard because of its ease and simplicity of manufacture.
The aforementioned problems have been largely obviated or at least reduced by the development of the mascara brush disclosed in the Hartel et al U.S. Pat. No. 4,733,425 which relies on bristles having a cross-sectional configuration, preferably cylindrical hollow, which bristles at least partially collapse or crimp when they are squeezed by the twisted wires so that the ends of the bristles flare outwardly to provide a more uniform pattern. However, while the Hartel et al mascara brush largely solves the appearance problem of the prior art, it creates new problems. Thus, because the bristles used in the Hartel et al mascara brush are preferably hollow, or at least have an irregular cross-section having flanges or ribs, the ends of the bristles exhibit significant capillary attraction for the liquid mascara and thus have a tendency to retain undeposited mascara after use. This in turn provides potential bacterial breeding sites. Another problem is that some of the bristles become weakened where they are grasped by the twisted wires, and this in turn provides a greater tendency for the bristles to break off and irritate the eye.